Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual page 84

NOTE:
Check to make sure that the following conditions are satisfied when using this "DTC Confirmation
Procedure".
• Intake air temp. : –8°C, 18°F or higher
• Engine coolant temp. : –8 – 110°C (18 – 230°F)
• Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
1) Connect scan tool with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data in ECM memory by using scan
tool and start engine.
3) Increase vehicle speed to 55 km/h (40 mph) or more.
4) Keep driving above vehicle speed till engine is warmed up completely (Change of vehicle speed is permitted
in this step).
5) Keep driving 50 – 60 km/h (30 – 40 mph) for 8 min. or more.
6) Stop vehicle and check if DTC and pending DTC exists by using scan tool. If not, check if oxygen sensor
monitoring test has completed by using scan tool. If not in both of above checks (i.e., no pending DTC and
oxygen sensor monitoring test not completed), check vehicle conditions (environmental) and repeat Steps 3)
through 6).
TROUBLESHOOTING (DTC P0136)
Step
1 Was "Engine Diag. Flow Table" performed?
2 HO2S-2 Output Voltage Check :
1) Connect scan tool to DLC with ignition
switch OFF.
2) Drive vehicle about 35 mph, 55 km/h for 2
min. or more.
3) Stop vehicle and check HO2S-2 output volt-
age displayed on scan tool while repeating
racing engine.
Is over and below 0.3 V indicated?
3 HO2S-2 Check :
1) With ignition switch OFF, disconnect HO2S-
2 coupler.
2) Connect voltmeter between "RED/GRN"
wire terminal (Canvas Top model) or "RED/
BLU" wire terminal (other than Canvas Top
model) and "GRY/YEL" wire terminal of
HO2S-2 coupler.
3) Start engine and check voltmeter while
repeating racing engine.
Is over and below 0.3 V indicated?
4 Short Term Fuel Trim Check :
1) Run engine at 2000 r/min. for 60 sec.
2) With engine idling, check short term fuel
trim displayed on scan tool.
Is it within –20 to +20%?
ENGINE GENERAL INFORMATION AND DIAGNOSIS (G16/J20 ENGINES) 6-79
Action Yes
Go to Step 2.
Go to Step 4.
"RED/GRN" (Canvas Top
model), "RED/BLU" (other
than Canvas Top model)
or "GRY/YEL" circuit open/
short.
If wire and connection are
OK, substitute a known-
good ECM (PCM) and
recheck.
Intermittent trouble or
faulty ECM (PCM).
Check for intermittent
referring to "Intermittent
and Poor Connection" in
Section 0A.
No
Go to "Engine Diag. Flow
Table".
Go to Step 3.
Replace HO2S-2.
Go to DTC P0171/P0172
Diag. Flow Table.